Frogworm is a frog with croll attached to chest harness(high), footloop with an added croll on it below the chest croll and roller, and a pantin/foot ascender on the other foot. Cross between Mitchell and Frog and sort of..like an inchworm system, but not really. Murphy system is just what Stridergdm said, it was "invented" when Dan Twilley forgot his upper ascender to his mitchell one day. Shrewsbury gave his to Twilley, and then used an extra foot ascender he just happened to have to make a system to climb Incredible pit in Ellisons. It is a Texas with a foot ascender on one foot, and a chest roller, and it is fast, although for me, uncomfortable after several thousand feet because foot ascenders tend to slightly twist my foot. At least all the ones I've tried so far. I know there's got to be countless more systems I'd love to try out, but I've only used these so far and a knot system that wasn't too bad in practice tree.